Fiber optic connectors are commonly employed to align and to interconnect one or more optical fibers with a variety of optical devices or with other optical fibers. For example, fiber optic connectors can be mounted on end portions of a pair of fiber optic cables, each of which include a number of optical fibers. The optical fibers of the fiber optic cables can, for example, transmit data or control signals between various remote devices, such as sensors or actuators, and a central control computer, such as a flight controller of an aircraft. The fiber optic connectors can then be interconnected such that the optical fibers of a first fiber optic cable are aligned with the optical fibers of a second fiber optic cable.
In order to efficiently transmit signals between optical fibers, the fiber optic connectors must precisely align the individual optical fibers such that the optical signals transmitted therethrough are efficiently coupled from fiber to fiber. Such alignment is particularly essential in connecting single mode optical fibers which generally have a light transmitting core of approximately 2-10 micrometers in diameter and which must be precisely aligned with the light-transmitting core of another single mode optical fiber of similar size in order to efficiently transmit optical signals therethrough.
In order to effectively couple optical signals from fiber to fiber, a fiber optic connector must maintain the precise alignment of the individual optical fibers in a predetermined manner such that the optical fibers will remain aligned as the fiber optic connecter is mated with another fiber optic connector or with other types of optical device. Therefore, a variety of methods have been developed to align individual optical fibers prior to sealing the optical fibers within the fiber optic connector.
For example, individual metallized optical fibers can be soldered to a support. In order to position the optical fiber, the solder bonding the metallized optical fiber to the support can be heated to a temperature above the predetermined melting temperature of the solder. Thereafter, the optical fiber can be moved and, once the optical fiber is properly positioned, the solder can be allowed to cool and resolidify to fix the position of the optical fiber relative to the support and, to the fiber optic connector. These systems typically require, however, some means, such as solder, for retaining an optical fiber in place after the optical fiber has been positioned in a separate alignment process, distinct from the means for retaining the optical fiber in position.
The alignment process can then be repeated to align the other optical fibers of the fiber optic connector prior to hermetically sealing the fiber optic connector. However, the heat required to allow one optical fiber to be positioned can oftentimes affect the position or alignment of adjacent optical fibers, thereby misaligning the adjacent optical fibers. In addition, these alignment and bonding systems and methods are generally relatively laborious and time-intensive, particularly, in instances in which a number of optical fibers must be individually aligned within the small volume of a single fiber optic connector.
More specifically, a fiber optic connector has been developed by AT&T Bell Laboratories and is described by R. J. Pimpinella in an article entitled "A New Type of Fiber Optic Connector Designed for Military Optical Backplanes", published in the Proceedings of the 42nd ECTC Conference on May 18-20, 1992, pages A-6-1 through A-6-5. This fiber optic connector includes a silicon base which defines a v-groove. An optical fiber can be positioned within the v-groove and a ball lens can be disposed adjacent an end portion of the optical fiber to form an optical fiber sub-assembly. The optical fiber sub-assembly can be mated with a second optical fiber sub-assembly, also comprised of an optical fiber and a ball lens mounted to a silicon base, such that the optical signals transmitted by a first optical fiber are collimated by the pair of ball lenses so as to be efficiently coupled to the second optical fiber. In order to prevent unnecessary exposure of the optical fiber to potentially harmful environmental influences, the optical fiber sub-assemblies can be disposed within respective self-sealing connector enclosures. In order to allow the first and second optical sub-assemblies to be mated, however, at least one of the connector assemblies has a spring-loaded cover that retracts upwardly to receive a corresponding portion of the other connector enclosure.
The fiber optic connector disclosed by R. J. Pimpinella as well as the above-described alignment methods and systems do not provide for the precise alignment of one or more optical fibers within a hermetically sealed package, such as a hermetically sealed fiber optic connector. Instead, the retraction of the spring-loaded cover of the connector enclosure of the fiber optic connector disclosed by R. J. Pimpinella can allow contaminants or moisture to enter the connector enclosure. In addition, the fiber optic connector disclosed by R. J. Pimpinella does not provide for realignment of the optical fibers without replacing the silicon bases in which respective v-grooves are defined. Further, the fiber optic connector disclosed by R. J. Pimpinella is also relatively difficult due to the recessed areas adjacent the ball lens.
As known to those skilled in the art, the precise alignment of an optical fiber within a hermetically sealed package is complicated since, in addition to precisely aligning the optical fiber in each of the six degrees of freedom, the alignment process must typically be performed without physically contacting or otherwise heating the optical fiber since heat, such as body heat, can cause the optical fiber to move due to thermal expansion, thereby misaligning the optical fiber. In addition, access to an optical fiber within a hermetically sealed package is generally limited since the optical device with which the optical fiber is being aligned is disposed within an internal cavity defined within the hermetic package.